1. Field of the Invention
The present disclosure relates to inorganic pigments, more particularly treated titanium dioxide, and a process for their preparation and their use in polymer compositions and polymer compositions having easy cleanability.
2. Description of the Related Art
High molecular weight polymers, for example, hydrocarbon polymers and polyamides, are melt extruded into shaped structures such as tubing, pipe, wire coating or film by well-known procedures wherein a rotating screw pushes a viscous polymer melt through an extruder barrel into a die in which the polymer is shaped to the desired form, and is then subsequently cooled and solidified into a product, that is, the extrudate, having the general shape of the die. In film blowing processes, as an extruded plastic tube emerges from the die the tube is continuously inflated by air, cooled, collapsed by rolls and wound up on subsequent rolls.
Inorganic pigments are added to the polymers. In particular, titanium dioxide pigments are added to polymers for imparting whiteness and/or opacity to the finished article. To deliver other properties to the molded part or film, additional additives are incorporated into the processing step. What is needed is a titanium dioxide that has multiple properties associated with it.
One of these properties is cleanability. One common way to impart cleanability to plastic articles is to incorporate a titanium dioxide pigment that causes the plastic article to be broken down by sunlight. The surface of the article is then renewed by washing of the article, for example, with rain. This process is called chaulking but suffers from the problem that the article is slowly eroded away.
What is needed is a pigmented plastic article having easy cleanability without the negative property of chaulking.